Chalara dieback of ash - update

1. Chalara dieback of ash - update Hugh Clayden Forestry Commission Scotland March 2013

2. Ash statistics/distribution • GB • 174,000 ha (net) of ash woodland • (5.8% of total woodland area) • Scotland • Occurs in 150,000 ha of woodland • 13,500 ha (net) of ash woodland • (1% of total woodland area; • 5% of broadleaved woodland area) • 10.7 million trees • 53 million seedlings 97% in private ownership

3. Ash statistics/distribution An assessment of the potential impacts of ash dieback in Scotland (Dr Rick Worrell)

4. Background to ‘Chalara’ • Caused by Hymenoscyphus pseudoalbidus - thesexual stage of • the fungus, Chalara fraxinea • Only known to infect species of Fraxinus • Spread by spores • Can infect ash seed • No evidence that C. fraxinea is harmful to human or animal health • Causes leaf loss, stem lesions and crown dieback in affected trees • Eradication no longer thought possible • Young trees tend to die quickly • Older trees can survive longer depending on location: • - woodland setting vs individual trees • - urban settings • - presence of honey fungus or other root-attacking agents • - climate and other environmental influences

5. Background to ‘Chalara’ • Natural resistance is expected in 1-2 (5)% of infected common ash • Susceptibility of other Fraxinus species varies (Manchurian ash • and white ash being the least affected) • Spores live for a few days only; can be dispersed 10s of kilometres • Main dispersal risk – plant movements; wind-blown spores • Low dispersal risk - people, animals/birds, timber • Disease progression of “up to 30km p.a.” • Infectious: June - October (peak July - August)

6. History • 1992 First observed in Poland and Lithuania • 2006 ‘Named’ as a new form of ash dieback • 2007 Placed on the EPPO alert list in 2007 • 2009 Responsible organism thought to be Hymenoscyphus albidus (common throughout mainland Europe and UK) • 2010 New molecular techniques allowed the disease to be correctly identified as H. pseudoalbidus • Surveys for H. albidus and H. pseudoalbidus

7. History Mid -1990s

8. History Late -1990s

9. History Early - 2000s

10. History Mid -2000s

11. History Late - 2000s

12. History 2011

13. History • 1992 first observed in Poland and Lithuania • 2006 ‘Named’ as a new form of ash dieback • 2007 Placed on the EPPO alert list in 2007 • 2009 responsible organism thought to be Hymenoscyphus albidus (common throughout mainland Europe and UK) • 2010 New molecular techniques allowed the disease to be correctly identified as H. pseudoalbidus • March 2012 Confirmed infection of ash at a Buckinghamshire • tree nursery (plants imported from mainland • Europe) • August 2012 Chalara confirmed on FES new planting site at • Knockmountain, Renfrewshire

14. History

15. History (cont) • Mid October 2012 Disease confirmed in ‘wider environment’ • in England • 29 October 2012 Temporary ban on import and movement • of ash plants and seeds • 2-6 November 2012 Rapid survey of ash woodlands across GB • 735 10km squares visited in Scotland • 2,720 sites surveyed • 5% of sites classed as ‘suspicious’ • Winter 2012/2013 National Forest Inventory site inspections • About 600 ‘trace forward’ inspections

16. Current position Confirmed site infections as at 22 March 2013 Scotland UK Nurseries 219 Recent planting 64 229 Wider environment 8 173 TOTAL 74 421

17. Current position